Method for packaging pressure feed devices



Dec. 21, 1965 N. J. BAUMANN METHOD RoR PACKAGING PRESSURE FEED DEVICESFiled Feb. 5, 1962 INVENTOR. NOREERTJ BAUM/ANN,

United States Patent O 3,224,158 METHD FOR PACKAGING PRESSURE FEEDDEVICES Norbert J. Baumann, South Fort Mitchell, Ky., assign'or to TheProcter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio FiledFeb. 5, 1962, Ser. No. 171,035 Claims. (Cl. 53-22) This inventionrelates to pressure feed devices and more particularly to a method usedin filling `and assembling a package adapted to dispense a productcontained therein by means of a floating or free piston subjected on oneside to the pressure exerted by a propellant.

In its most familiar form, a pressurized dispensing device comprises asealed can, the interior of which is filled with product and propellant.The can top is provided with a dispensing valve which is adapted torelease the product in either the erect or inverted position, dependingupon whether or not a dip tube is used. If the valve is opened when thecontainer is in the incorrect position, the propellant will escape andthe consumer will not be able to remove the balance of the product.

Other types of pressurized pack-ages have been devised to avoid theintimate contact between product and propellant and to obviate thepossibility of loss of propellant as mentioned above. For example, somedevices have been proposed wherein the propellant is sealed within aflexible and expansible sack which is impervious to both product andpropellant. With this type of package, as the valve is opened andpr-oduct flows outwardly the product pressure drops, thereby permittingthe sack to expand in order to equalize the product and propellantpressures, the expansion forces the displaced volume of product throughthe valve, at least until the valve is closed, whereupon expansion ofthe sack continues until both the pressures are in equilibrium. Thisdevice is not only expensive but in many cases fails to dispensesubstantially all of the product contained within it because of the sackblocking the means of product egress.

A more practical means for separating product and propellant inpressurized packages involves the use of a floating or free piston todivide the package interior into two chambers-a product and a propellantchamber. To date, however, the free piston pressure package has notgained commercial success due to the high cost of such a package and tothe relatively high percentage of failures within each type of designtested. Some common types of failure are loss of propellant throughcorrosion or piston blow-by followed by escape through the productvalve. It should be noted that in either of these cases the result wouldbe a device which is inoperative.

The presently known piston type pressurized packages are usuallyassembled in this way: first, the piston is inserted in the bottom ofthe can; next, the bottom, containing a filling grommet, is seamed inplace; third, the product is placed in the product chamber; fourth, aproduct dispensing valve is seamed in place; fifth, a filling needleintroduces the propellant into its chamber by piercing the self-sealinggrommet, injecting the propellant and then withdrawing from the grommetupon completion of the charging operation.

The above-mentioned assembly method has been found to require, in somecases, means for placing the product underla higher pressure than thepropellant (eg, use of spring means pressing on the propellant side ofthe piston) in order to prevent propellant blow-by. Further, in manycases it has been found that it is not commercially feasible to producesuch a package (utilizing the filling needle-grommet technique) at highspeeds.

It is an object of the present invention to obviate the abovedifficulties.

Another object of the present invention is to provide an economical andcommercially feasible method of packaging .a product in a piston-typepressurized dispensing container, resulting in a package in which thepropellant is securely confined within the propellant chamber and inwhich corrosion of the can interior, oxidation of the product andbacterial development within the package are inhibited.

Brieiiy stated, in accordance with one aspect of this invention, themethod comprises placing the product in an open-bottom container body,drawing a vacuum upon the unfilled volume of the container body,inserting a piston in the open bottom while maintaining the vacuum,causing the piston to be forced into intimate contact with the productand to displace some product from its filled position to form a productseal between the piston and the container body, `breaking the vacuumacting upon the container body, purging the propellant chamberconstituting the remaining unfilled volume of the container body with asubstantially inert gas, sealing a valve equipped container bottom tothe container body and pressurizing the container by forcing apropellant into the propellant chamber through the valve in thecontainer bottom.

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter which is regarded as thepresent invention, it is believed that the invention will be betterunderstood from the following description taken in connection with theaccompanying drawings in which:

FIGURE 1 is a perspective view in section of a free piston type ofcontainer, the filling and assembling of which may be performed inaccordance with the present invention;

FIGURE 2 is an elevation, partly in section, of the container body,following the filling operation;

FIGURE 3 is a fragmentary view in section illustrating one form ofapparatus which may be used in inserting a piston into a filledcontainer body;

FIGURE 4 is a fragmentary view in section disclosing a means for purgingthe propellant chamber;

FIGURE 5 is a fragmentary view in section of a product filled,piston-equipped, purged container body with a valve-equipped bottom wallplaced thereon in position for seaming;

FIGURE 6 is a fragmentary view in section illustrating the manner inwhich the package of FIGURE 1 is pressurized following the seaming ofthe bottom wall; and

FIGURE 7 is an enlarged fragmentary view showing the action of thebottom wall valve while propellant is being forced into the container asin FIGURE 6.

Referring to FIGURE l of the drawing, a package 10 to be preparedaccording to the herein disclosed process is shown as being constructed-of a cylindrical body 11 having a neck portion 12 at the terminal endof cone-like top Wall 13. A dispensing valve 14 is mounted upon thepackage by seaming valve insert or cup 15 to neck portion 12. The valve14 and valve cup 15 which are unitized by crimping the valve 14 withinthe valve chamyber 16 of the valve cup 15 are commercially availableunits and the details of their structure will be fully understood bythose skilled in the art.

Product P which could be toothpaste, mustard or any other type ofproduct desired to be packaged for dispensing from a pressurizedcontainer is located in the upper portion of the container body 11adjacent dispensing valve 14. A hollow piston 17 comprising contouredface 18 and tapered depending skirt 19 is found within the package 10below the product P. The lower end of the tapered skirt 19 has anoutside diameter which is substantially identical with the insidediameter of the cylindrical body 11 thereby providing a snug sliding fitfor the piston within the package 10. The propellant chamber 20 formedby the hollow interior of piston 17 and bottom wall 21 seamed to thelower end of a cylindrical body 11 contains propellant adapted to movethe piston 17 upwardly to discharge the product P upon actuation of thedispensing valve 14. The contours of face 18 closely match the combinedinterior surfaces of the container top wall 13, valve 14 and valve cup15 thereby permitting substantially all of the product P to eventuallybe dispensed from the package 10 through dispensing valve 14 at theuppermost limit of piston 17 movement. The bottom wall 21 has anaperture 22 extending therethrough which is adapted to serve as a portfor the introduction of propellant into the chamber 2t). Overlying theaperture 22 and covering a continuous portion of the interior surface ofbottom wall 21 surrounding aperture 22 is a valve element 23. While thepresent invention is not dependent upon the type of propellant valveused, the preferred type comprises valve element 23 which is anelastically distensible, substantially propellantimpermeable film coatedon one side with a layer of pressure sensitive adhesive. It is Wellknovtm that the pressure sensitive adhesives are composed of anelastomer plus a resin, the elastomer providing the internal strengthand the resin the adhesion. Preferably, the film or backing may be madeof polymerized vinylidene chloride or a modified polyethylene, althoughany material having the necessary elastomeric or impermeabilityproperties would be suitable. The coating of pressure sensitive adhesivemay also be varied depending upon the type of propellant to be used andthe composition of other substances to which the adhesive must beexposed. The specific type of adhesive and backing best suited for aparticular package or product is, of course, merely a matter of properselection of many commercially available pressure sensitive tapes.

' Referring again to aperture 22, it is extremely important that theaperture be free from sharp burrs where it terminates on the innersurface of the bottom wall 21 so as to avoid puncturing the valveelement 23 and causing the valve to fail by leakage through thepunctures. One method of avoiding such burrs is to punch the aperturethrough from the inner surfaces. It is also important that the aperture22 diameter be small enough to prevent valve element 23 from beingforced through the hole at pressures needed to operate the package. Inthis connection it has been found advantageous to size the aperture 22in the range of 1/32 to %4, which is large enough to permit the use oftools of sufficient strength to make production techniques in formingthe aperture practical and yet small enough to prevent failure of thevalve element 23 as noted above.

As is usually the case in the field, preferred materials to be used inconstructing the container body and bottom wall of the package describedabove would be a metal such as aluminum or a tin plated steel. Thepiston 17 is is illustrated in FIGURE 3.

desirably constructed of a resilient, moldable plastic such aspolyethylene.

FIGURE 2 illustrates the condition of the package at the beginning ofthe process performed in accordance with the present invention, It willbe noted that an openbottomed container body 11 having seamed thereon adispensing valve and valve cap unit is presented in inverted conditionto a filling mechanism 24. Filling mechanisms such as is illustrated by24 are well known in the art and for this reason no detailed disclosureof means which may be utilized in holding the container in the invertedposition and metering and timing means for injecting the product to befilled is shown. In the illustration a ller nozzle 25 is shown in itsfilling position, the lowermost in its cycle, in the interior of thecontainer body 11 whereat it is possible to avoid splashing andspattering of product during the filling operation. A valve stem 26 istelescoped within the interior of ller nozzle 25 and by means not shown,reciprocated along the lengthwise axis of the filler nozzle in propertiming with the filling cycle, thereby intermittently and alternatelywithdrawing and returning stem tip 27 from sealing engagement withnozzle orifice 28. Thus, it will be seen that the empty container isplaced in the filling mechanism, the ller nozzle and the thereincontained valve stem and tip are lowered into the interior of thecontainer body 11, the stem tip is raised thereby unsealing nozzlelorifice 28, a measured amount of product P is permitted to flow throughnozzle orifice 28 into the container body 11. Thereafter, the stem tip27 is brought back into sealing engagement with nozzle orifice 28 andthe filler nozzle removed from the container interior.

Following the filling opertaion, the inverted productcontaining body 11has inserted therein the piston 17. One means by which such insertionmay be accomplished As shown, the apparatus comprises a vacuum chamber29 which is adapted to move along a vertical path. The chamber 29 issubstantially cup-shaped, with an apertured top wall 30 and cylindricalside wall 31A Along the bottom edge of the side wall 31 is attached, byadhesives or otherwise, a gasket member 32 formed from a resilientelastomeric material. A hose fitting 31a is engaged within an aperture31b in the side wall 31. Attached to the protruding portion of thefitting 31a, is a hose 31C extending to a two position valve connectedto a source of vacuum and an atmospheric vent, none of which are shown.Thus, with the valve in one position the hose 31c is vented to theatmosphere and in the alternate position the hose 31e is incommunication with the vacuum source. The aperture 33 of top wall 30functions as a guide for and is in sliding engagement with the tube 34extending from a plunger head 35 located within the vacuum chamber 29.The tube 34 is hollow and cylindrical and attached to the top thereof isa hose 36. The hose 36 is connected to means for selectivelyestablishing communication with a pressurized inert gas supply or to asource of vacuum. The specific structural details of the gas and vacuum.pulling system as well as the means for selectively integrating suchsystems with a machine cycle so as to result in the proper timing andsynchronization therewith are not critical and many variations thereofare well known in the art.

The plunger head 35 is engaged with the lower end of tube 34 which ispressed into counterbore 37 of passageway 38 extending through theplunger head 35 in a vertical direction. The plunger head may betrapezoidal in vertical cross-sectional configuration and cylindrical inhorizontal cross-section, as shown, thus taking on the appearance of alarge bottle stopper. The size of the plunger head 35 is slightlysmaller than the piston 17 interior. Alternatively, Where the piston 17is constructed of thin materials or where distortion of the piston 17 isotherwise a problem, the plunger head 35 may be made to conform with theshape of the piston 17 interior.

In performing the insertion process, the partially completed package isplaced in vertical alignment with the vacuum chamber 29. While thevacuum chamber and the plunger head contained therein are in the raisedposition, the piston 17 which is to be inserted in the package is placedupon the plunger heady 35. It will be noted that the plunger head 35 isadapted to telescope within the interior of the piston 17 and that itslower surface along an area thereof surrounding `aperture 38 contactsthe contoured face 18 o-f the piston interior. At the time of placementof the piston 17 on the plunger head 35, a vacuum is pulled through theinterior of hose 36, tube 34 and passageway 38, therewith causingatmospheric pressure to secure the piston 17 against the plunger head 35and maintain it in mounted position thereon.

Following the above, the vacuum chamber 29 along with the plunger head35 and the vacuum secured piston 17 are lowered as a unit until thegasket member 32 engages with the outwardly flaring portion 39 of thecontainer body 11, making a hermetic seal therewith. Then the tube 34and the attached plunger head 35 are lowered, by means not shown, untilthe piston 17 assumes the position shown by phantom lines in FIGURE 3,at which point the tube 34 may, by a latching mechanism, be temporarilylocked in place.

Next, the two position valve is actuated to place it in a positionpermitting a vacuum to be pulled by the vacuum source through hose 31Cand the passageway in hose tting 3117, withdrawing air from within thevacuum chamber 29 and from the unfilled bottom portion (11a as shown inFIGURE 3) of container body 11. In this connection, it will be notedthat the evacuation of the bottom portion 11a of container 11 isaccomplished through an annular space 40 intermediate the periphery ofpiston 17 and the interior surface of container body 11 with the pistonin the phantom position of FIGURE 3. With respect to the desirability-of the positioning of the piston so as to create the annular space 40,it should be realized that when subjected to a sudden high vacuum manyproducts will expand to occupy several times their initial volume due toentrapped or otherwise free air in the product. While a slowlyincreasing vacuum taken over an extended period would eliminate suchproblems, such a process would prevent high speed, efficient production.In the present invention the problem has been solved by affording arelatively narrow escape passageway (annular space 40) through which airmay egress from unfilled bottom portion 11a and from the product itself.The space 40 is too narrow to permit bubbles of product to escape andconsequently the bubbles break as they move into its confines, freeingthe entrapped air and permitting the use of a high vacuum surge forevacuating at high speed production rates. The preferable range ofseparation of the periphery of piston 17 and the interior surface of thecontainer body 11 at the point at which the two are most closelyadjacent (i.e. the thickness of space 40) for a product will varyaccording to the viscosity of that particular product, but it has beenfound that such thicknesses in the range of from about .001 to about.020" is highly satisfactory for most products.

When the vacuum within the chamber and container reaches a predeterminedvalue or following the lapse of an equivalent interval of time, the tube34 and plunger head 35 are lowered to force the piston 17 further intothe container to the point where the piston 17 displaces sufficientmaterial to form a solid wedge-shaped annular seal such as isillustrated at 41 of FIGURE 4. Such a function can be performed, forexample, by unlatching the tube 34 and utilizing gravitational forcesacting on a weighted means attached to tube 34 and having su'icient massto cause such displacement andv ultimate relocation of displacedmaterial in the product seal area 41. Alternatively, mechanical meanscould be adapted to lower the piston 17 a predetermined amount to thuscause a similar result. It has also been determined possible to achievethe seal by means of a pressure -blow system wherein the piston 17 ispropelled by high pressure or high velocity gas emanating frompassageway 38.

Following the placement of the piston 17 within the container body 11and the formation of the product seal 41, the selective control systemto which hose 36 is connected places the hose 36 in communication with asupply of inert gas having the pressure in excess of atmospheric. Thusthe vacuum engagement of plunger head 35 and piston 17 is released.Simultaneously, the two position valve connected to hose 31C is switchedto its alternate position and the vacuum chamber vented, thereby raisingthe gas pressure within the vacuum chamber 29 to atmospheric condition.Next, the tube 34 and the attached plunger head 35 are raised intoposition within the enclosure formed by the vacuum chamber 29 and theseelements raised as a unit away from the outwardly aring portion 39 ofcontainer body 11 permitting the partially formed package to be removed.

At this point the remaining unfilled volume of the partially formedpackage, the propellant chamber 20 which lies within the piston member17, is filled with a mixture of air and the inert gas utilized inbreaking the suction engagement between the plunger head 35 and thepiston 17. If the package were to be sealed in such a condition theoxygen and moisture contained therein would provide conditions conduciveto corrosion of the can interior, oxidation of product and developmentof bacterial colonies. In order to eliminate such an undesirableenvironment, the piston 17 interior is purged by means of an inert gas.This operation may be performed as illustrated in FIGURE 4 wherein a gasnozzle 42 directs a stream of gas 43 downwardly into the pistoninterior, displacing any air contained therein. Alternatively of course,this same operation could be performed by the apparatus of FIGURE 3 soas to occur subsequent to the piston insertion step, utilizing the inertgas system previously described in connection with disengagement of thepiston 17 and plunger head 35. Immediately thereafter, the bottom wall21 is placed in position with its seaming flange properly aligned -withthe outwardly Haring portion 39 of the container body 11. In this mannerthe inert gas -is maintained within the confines of the package until bystandard operations a bottom seam 44 is obtained.

After the bottom seam is made, the product filled package is completelyassembled and ready for pressurization. One form of apparatus adapted toperform this function is shown in FIGURE 6 and comprises a metallicplunger 45 with a blind coaxial hole 46 and a counterbore 47 withinwhich is retained a resilient sealing insert 48, preferably acylindrical rubber tube. A tting 49, which is fastened to the side wallof the plunger 45 by means which are well known in the art, has a bore50 therethrough aligned with a passageway 51 communicating with hole 46.A tube 52 which is telescoped over the protruding end of tting 49 isconnected with a source of pressurized propellant and with a valve andcontrol arrangement to regulate the ow of propellant, neither of whichis shown in the drawing.

The propellant can be metered or otherwise controlled by volumetricmeasurement or possibly maintained at a pressure desired in thepropellant chamber and the charging controlled by merely balancing thepressures. Of course many other methods of regulating the quantity ofpropellant to be introduced into the chamber may be used and it is notimplied that the methods disclosed herein are the only ones suitable foruse with such equipment.

It is seen in FIGURE 6 that the package to be pressurized is invertedand held in a relatively xed relationship with the plunger 45 by meansnot shown on the drawing. The plunger 45 is then lowered so that sealinginsert 48 encompasses the outer surface of bottom Wall 21 surroundingaperture 22. Sucient pressure is 7 applied to plunger 45 to provide atight seal between the sealing insert 48 and the bottom wall 21. At thispoint the valve and control arrangement is actuated causing thepropellant to fiow into tube 52 through bore 50, passageway 51, hole 46and the interior of sealing insert 48. When the propellant reachesaperture 22 it is forced therethrough and the pressure acts upon theunderside of the valve element 23 which overlies aperture 22. Thepressure acting upon the valve element 23 forces the area acted upon tobulge inwardly as shown in FIGURES 6 and 7 stretching the elastic filmand causing a portion of the element 23 to become separated from thebottom wall 21 along a narrow vent line interconnecting the aperture 22with the propellant chamber 20. The portion of element 23- thusseparated from the bottom wall to form the Vent is also permitted to bedistended inwardly by means of the elastic properties of the lm. Thebulge under aperture 22 and along the vent line continues to be presentuntil the source of pressurization is removed or until the pressure ofthe propellant within the propellant chamber 20 approximately balancesthat within the sealing insert 48, at which point the elastic propertiesof the valve element 23 cause the vent to close, sealing the propellantwithin the chamber 20 and causing the pressure sensitive adhesive tobecome reattached to the bottom Wall 21 along the vent line.

As soon as the sealing insert 48 is removed from sealing contact withthe outer surface of bottom wall 21, thus venting the aperture 22 to theatmosphere, the pressure of the propellant within the chamber 20 causesa tight seal between the valve element 23 and the portions of the bottomwall surrounding the aperture 22.

Any number of propellants might be suitable for use in packages such asabove described; however, for simplicity, economy and general use,nitrogen with an initial pressure of about 100 p.s.i.g. is preferred.

While the above-described valve element 23 comprised a tape valve, itwill be understood that any type of resealable valve which is alsocapable of maintaining the inert gas 43 within the propellant chamber 20prior to pressurization would be suitable if production rates were notcritical. In this connection a self-sealing grommetinjection needlesystem would be adapted to use on containers to be processed accordingto the subject invention.

By the above-described process there is economically obtained a freepiston package which is not susceptible to interior corrosion, productoxidation or propellant piston bloWby. It is a process which is capableof high speed performance on modern machines. While the abovedescription mentioned a single vacuum chamber 29 it will be understoodthat a battery of such equivalent chambers could be mounted about theperiphery of rotary packaging equipment to conform with the high speedrequirements of modern packaging concerns. Many other modifications ofthe above invention may be used and it is not intended to hereby limitit to the particular embodiment shown or described. The terms used indescribing the invention are used in their descriptive sense and not asterms of limitation it being intended that all equivalents thereof beingincluded within the scope of the appended claims.

What is claimed is:

1. The method of packaging a piston-type pressurized product dispensingcontainer which comprises:

(A) filling an open-bottom container body having a product dispensingvalve mounted at the top thereof with a quantity of the product to bedispensed, said filling being accomplished through said open-bottomwithv the container body in an inverted position;

(B) drawing a vacuum upon" the unfilled volume of said container bodywhile insertinga tapered piston in said open bottom;

(C) causing the piston to be forced into intimate contact with saidproduct along its lower face and to displace some product from itsfilled position into a continuous wedge-'shaped annular product sealbetween the tapered outer peripheral surface of said piston and theadjacent interior surface of said container body;

(D) breaking the vacuum acting upon the container body;

(E) purging substantially all of the oxygen from the propellant chamberconstituting the piston interior and the remaining unfilled volume ofthe container body by displacement of air with a substantially inertgas;

(F) applying a valve equipped container bottom and seaming it to thelower edge of the container body, and

(G) pressurizing the container by forcing a propellant into thepropellant chamber through the valve in said container bottom.

2. In the process of packaging a pressurized package utilizing a taperedpiston for exerting propellant pressure upon the product to bedispensed, the steps which comprise:

(A) filling an open-bottom container body through said open bottom witha quantity of said product,

(B) drawing a vacuum upon the unfilled volume of said container bodywhile maintaining said tapered piston in a position whereby exhaustionof any gas within the said unfilled volume is accomplished by gas-flowthrough a narrow annular passageway formed between the interiorcontainer body wall and the exterior wall of said piston,

(C) forcing the piston into intimate contact with said product anddisplacing some of said product from its filled position into acontinuous wedge-shaped annular product seal between the exterior wallof said piston and the adjacent interior container body wall,

(D) breaking the vacuum acting upon the container ybody,

(E) applying a valve equipped container bottom and seaming it to thelower edge of the container body, and

(F) pressurizing the container by introducing propellant into thepropellant chamber through the valve in said container bottom.

3. The process of claim 2 in which the thickness of said annular passagelies in the range of from .001 to .G20 inch.

4. In the process of packaging a pressurized package Autilizing atapered piston for exerting propellant pressure upon the product to bedispensed, the steps which comprise:

(A) filling an open-bottom container body through said open bottom witha quantity of said product,

(B) drawing a vacuum upon the unfilled volume of said container bodywhile maintaining said tapered piston in a position whereby exhaustionof any gas within the said unfilled volume is accomplished by gas-flowthrough a narrow annular passageway formed between the interiorcontainer body wall and the exterior wall of said piston,

(C) forcing the piston into intimate contact with said product anddisplacing some of said product from its filled position into acontinuous wedge-shaped annular product seal between the exterior wallof said piston and the adjacent interior container body wall,

(D) breaking the vacuum acting upon the container body,

(E) purging substantially all of the oxygen from the propellant chamberformed by the piston interior and the remaining unfilled volume of thecontainer body by displacement of air with a substantially inert gas,and

(F) applying a container bottom and placing a propellant in saidpropellant chamber.

5. The method of packaging a pis-ton-type pressurized product dispensingcontainer which comprises:

(A) iilling an open-bottom container body having a product dispensingvalve mounted at the top thereof with a quantity of the product to bedispensed, said filling being accomplished through said open-bottom withthe container body in an inverted position;

(B) drawing a vacuum upon the unfilled volume of said container bodywhile inserting a tapered piston in said open bottom;

(C) causing the piston to be forced into intimate contact with saidproduct along its lower face and to displace some product from itsiilled position into a continuous wedge-shaped annular product sealbetween the tapered outer peripheral surface of said piston and theadjacent interior surface of said container body;

(D) breaking the vacuum acting upon the container body;

(E) applying a valve equipped container bottom and searnng it to thelower edge of the container body,

and

References Cited by the Examiner UNITED STATES PATENTS Pyenson 53-22 XKaye et al. 222-387 X Mills 53-7 X Mahon et al 53--36 X Harmon et al53-22 X FRANK E. BAILEY, Primary Examiner.

ROBERT A. LEIGHEY, Examiner.

5. THE METHOD OF PACKAGING A PISTON-TYPE PRESSURIZED PRODUCT DISPENSINGCONTAINER WHICH COMPRISES: (A) FILLING AN OPEN-BOTTOM CONTAINER BODYHAVING A PRODUCT DISPENSING VALVE MOUNTED AT THE TOP THEREOF WITH AQUANTITY OF THE PRODUCT TO BE DISPENSED, SAID FILLING BEING ACCOMPLISHEDTHROUGH SAID OPEN-BOTTOM WITH THE CONTAINER BODY IN AN INVERTEDPOSITION; (B) DRAWING A VACUUM UPON THE UNFILLED VOLUME OF SAIDCONTAINER BODY WHILE INSERTING A TAPERED PISTON IN SAID OPEN BOTTOM; (C)CAUSING THE PISTON TO BE FORCED INTO INTIMATE CONTACT WITH SAID PRODUCTALONG ITS LOWER FACE AND TO DISPLACE SOME PRODUCT FROM ITS FILLEDPOSITION INTO A CONTINUOUS WEDGE-SHAPED ANNULAR PRODUCT SEAL BETWEEN THETAPERED OUTER PERIPHERAL SURFACE OF SAID PISTON AND THE ADJACENTINTERIOR SURFACE OF SAID CONTAINER BODY; (D) BREAKING THE VACUUM ACTINGUPON THE CONTAINER BODY; (E) APPLYING A VALVE EQUIPPED CONTAINER BOTTOMAND SEAMING IT TO THE LOWER EDGE OF THE CONTAINER BODY, AND (F)PRESSURIZING THE CONTAINER BY FORCING A PROPELLANT INTO THE PROPELLANTCHAMBER THROUGH THE VALVE IN SAID CONTAINER BOTTOM.